The Collaborative International Dictionary of English v.0.48:

Overnice \O"ver*nice"\, a.
   Excessively nice; fastidious. --Bp. Hall. -- O"ver*nice"ly,
   adv. -- O"ver*nice"ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

overnice
    adj 1: excessively fastidious and easily disgusted; "too nice
           about his food to take to camp cooking"; "so squeamish he
           would only touch the toilet handle with his elbow" [syn:
           dainty, nice, overnice, prissy, squeamish]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "overnice":
   Gongoresque, Gongoristic, Marinistic, affected, artificial, chichi,
   elaborate, elaborated, elegant, euphemistic, euphuistic, exquisite,
   formalistic, goody good-good, goody-goody, hairsplitting,
   hypercritical, hyperelegant, hypersensitive, la-di-da, mannered,
   mincing, morbidly sensitive, namby-pamby, overconscientious,
   overcritical, overelaborate, overelegant, overfastidious,
   overmeticulous, overparticular, overprecise, overrefined,
   overscrupulous, oversensitive, oversqueamish, pedantic, precieuse,
   precieux, precious, precisian, precisianistic, precisionistic,
   pretentious, puristic, simpering, studied, ultracritical,
   unnatural